The German physicist Otto von Guericke (1602-1686), known for his invention of the vacuum pump, also investigated the properties of air and the atmosphere.

Otto von Guericke was born on November 20, 1602, in Magdeburg (then in Prussian Saxony and now Germany). At the age of 15 he entered the University of Leipzig, where he studied jurisprudence, and continued his study of law at Jena and Helmstedt. In 1623 he went on to the University of Leiden, where he pursued mathematics, mechanics, and military engineering.

After traveling in France and England, Guericke returned to Magdeburg, where he married the daughter of a prominent local politician in 1626. He became active in politics and was elected to the city council in 1627. In 1631 the city was sacked and burned by the invading imperial armies; Guericke and his family barely escaped with their lives. Upon Magdeburg's liberation the following year Guericke returned as a military engineer and once again became actively involved in politics. He was reelected to the city council. In 1646 he became one of the four burgomasters of Magdeburg and served in that capacity for the next 35 years. He retired to Hamburg and there died on May 11, 1686.

Scientific Investigations

In spite of his active political life Guericke managed to pursue his scientific interests as well. He had become increasingly interested in the current debates concerning the possible existence of a vacuum and set out to experimentally investigate the problem. When he actually invented his vacuum pump is uncertain, though it was apparently about 1650. He had begun his experimental researches much earlier, and the instrument underwent a gradual evolution, having begun simply as a modified water pump. Attempting to create a vacuum by pumping out the contents of a sealed container, Guericke sealed a wooden barrel, filled it with water, and then, using a pump, withdrew the water, believing that as the water was removed from below, a vacuum would be produced above it. As the water was withdrawn, however, air could be heard rushing into the barrel through the pores in the wood.

After several failures and modifications Guericke succeeded in evacuating a large, specially constructed sphere made of metal and connected with carefully fitted parts to a pump. Utilizing his first vacuum pump Guericke was able to obtain fairly high vacuums in the metal spheres. His most dramatic demonstration of the effects of this vacuum took place before Emperor Ferdinand III and the assembled Reichstag in Regensburg in May 1654. Two bronze hemispheres--known ever since as the Magdeburg hemispheres--were carefully fitted edge to edge and evacuated. Two teams of eight horses each were attached to this globe, one to each side, but they were unable to separate the hemispheres. When the air was allowed to reenter, however, the two hemispheres fell apart of their own accord.

Guericke has traditionally been credited with important contributions to electricity and is generally cited as having constructed the first frictional electrical machine. This device consisted of a large globe of sulfur mounted on an axis in such a manner that it could be rotated rapidly. When Guericke rubbed the rotating globe with a dry hand, he observed the attraction and repulsion of feathers near it, as well as other effects which are today recognized as electrical in origin. It should be emphasized, however, that Guericke's sulfur globe was not devised to investigate the properties of electricity but to illustrate what he saw as certain innate virtues (such as attraction) which existed in all matter. Nowhere does he refer to the effects of his globe as electrical, and not until the following century was their electrical nature recognized.

Most of Guericke's researches were described and published for the first time in his New Magdeburg Experiments on Empty Space (1672), a Latin work devoted largely to cosmology. However, he had completed his researches much earlier, and his experiments with the vacuum pump were described in 1657 in an appendix to a work by Kaspar Schott, a professor of physics and mathematics at Würzburg.

Further Reading

• There is no major work on Guericke in English and no English translation of the New Magdeburg Experiments. Information on Guericke is in Ernst Mach, The Science of Mechanics: A Critical and Historical Account of Its Development (trans. 1893; 5th ed. 1942), which includes a discussion of Guericke's experiments, and Lynn Thorndike, A History of Magic and Experimental Science , vols. 6 and 7 (1958).